.beta.-galactosidase is a conventional marker enzyme which is used in immunological test procedures. However, in most cases a considerable measurement time is required to carry out such test procedures which under certain circumstances, e.g. in determinations which have to be carried out quickly following accidents and in medical emergency situations, can cause a life-threatening delay in the onset of the necessary therapeutic procedures. There is therefore a great need to shorten these reaction times.
Moreover, the antibodies needed for such immunological test procedures can usually only be produced by means of extremely complicated procedures which is another reason to try to keep the amount of antibodies required for such a test as small as possible. Since, however, when the amount of antibodies is decreased there are also less marker enzymes present in the enzyme-immunoassay, the sensitivity of the detection reaction also decreases.
On the other hand, it is also possible to use a smaller amount of the substance to be examined by increasing the sensitivity of such immunological test procedures. This is of particular importance when only a limited amount of the substance to be examined is available and a multitude of analytical tests is to be carried out on it.
It is therefore the aim of the invention to overcome the previously-mentioned disadvantages and to provide a test method with an increased sensitivity.